sections

1 Introduction to thePeriodic Table

2 Representative Elements

3 Transition ElementsLab Metals and NonmetalsLab Health Risks from Heavy

Metals

Virtual Lab How is an atomsstructure related to its positionon the periodic table?

Skyscrapers, Neon Lights,and the Periodic TableMany cities have distinctive skylines. What istruly amazing is that everything in this pho-tograph is made from 90 naturally occurringelements. In this chapter, you will learnmore about the elements and the table thatorganizes them.

Think of an element that youhave heard about. Make a list of the properties you know andthe properties you want to learn about.

Science Journal

The PeriodicTable

Jim Corwin/Index Stock

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Periodic Table Make thefollowing Foldable to helpyou classify the elements in

the periodic table as metals, nonmetals, andmetalloids.

Fold a vertical sheetof paper from sideto side. Make thefront edge about1.25 cm shorterthan the back edge.

Turn lengthwiseand fold intothirds.

Unfold and cut only the top layeralong both folds to make three tabs.Label each tab as shown.

Find Main Ideas As you read the chapter, writeinformation about the three types of elementsunder the appropriate tabs. Use the informationin your Foldable to explain how metalloidshave properties between those of metals andnonmetals.

STEP 3

STEP 2

STEP 1

Make a Model of a PeriodicPatternEvery 29.5 days, the Moon begins to cyclethrough its phases from full moon to newmoon and back again to full moon. Eventsthat follow a predictable pattern are calledperiodic events. What other periodic eventscan you think of?

1. On a blank sheet of paper, make a grid withfour squares across and four squares down.

2. Your teacher will give you 16 pieces ofpaper with different shapes and colors.Identify properties you can use to distin-guish one piece of paper from another.

3. Place a piece of paper in each square onyour grid. Arrange the pieces on the gridso that each column contains pieces thatare similar.

4. Within each column, arrange the pieces toshow a gradual change in their appearance.

5. Think Critically In your Science Journal,describe how the properties change in therows across the grid and in the columnsdown the grid.

Start-Up Activities

Preview this chapters content and activities at blue.msscience.com

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Metals NonmetalsMetalloids

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434 CHAPTER 15 The Periodic Table

Development of the Periodic TableEarly civilizations were familiar with a few of the substances

now called elements. They made coins and jewelry from gold andsilver. They also made tools and weapons from copper, tin, andiron. In the nineteenth century, chemists began to search for newelements. By 1830, they had isolated and named 55 different ele-ments. The list continues to grow today.

Mendeleevs Table of Elements A Russian chemist,Dmitri Mendeleev (men duh LAY uhf), published the first ver-sion of his periodic table in the Journal of the Russian ChemicalSociety in 1869. His table is shown in Figure 1. When Mendeleevarranged the elements in order of increasing atomic mass, hebegan to see a pattern. Elements with similar properties fell intogroups on the table. At that time, not all the elements wereknown. To make his table work, Mendeleev had to leave threegaps for missing elements. Based on the groupings in his table,he predicted the properties for the missing elements.Mendeleevs predictions spurred other chemists to look for themissing elements. Within 15 years, all three elementsgallium,scandium, and germaniumwere discovered.

Describe the history of the peri-odic table.

Interpret an element key. Explain how the periodic table is

organized.

The periodic table makes it easierfor you to find information that youneed about the elements.

Review Vocabularyelement: a substance that cannotbe broken down into simplersubstances

New Vocabulary

period group representative element transition element metal nonmetal metalloid

Introduction to the Periodic Table

Figure 1 Mendeleev published his first periodictable in 1869. This postage stamp, with his table andphoto, was issued in 1969 to commemorate the event.Notice the question marks that he used to mark hisprediction of yet-undiscovered elements.

Stamp from the collection of Prof. C.M. Lang, photo by Gary Shulfer, University of WI Stevens Point

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Moseleys Contribution Although Mendeleevs table cor-rectly organized most of the elements, a few elements seemedout of place. In the early twentieth century, the English physicistHenry Moseley, before age 27, realized that Mendeleevs tablecould be improved by arranging the elements according toatomic number rather than atomic mass. Moseley revised theperiodic table by arranging the elements in order of increasingnumber of protons in the nucleus. With Moseleys table, it wasclear how many elements still were undiscovered.

Todays Periodic Table In the modern periodic table on the next page, the elements

still are organized by increasing atomic number. The rows orperiods are labeled 17. A period is a row of elements in theperiodic table whose properties change gradually and pre-dictably. The periodic table has 18 columns of elements. Eachcolumn contains a group, or family, of elements. A group con-tains elements that have similar physical or chemical properties.

Zones on the Periodic Table The periodic table can bedivided into sections, as you can see in Figure 2. One sectionconsists of the first two groups, Groups 1 and 2, and the elementsin Groups 1318. These eight groups are the representativeelements. They include metals, metalloids, and nonmetals. Theelements in Groups 312 are transition elements. They are allmetals. Some transition elements, called the inner transition ele-ments, are placed below the main table. These elements are calledthe lanthanide and actinide series because one series follows theelement lanthanum, element 57, and the other series followsactinium, element 89.

SECTION 1 Introduction to the Periodic Table 435

Transition elements

Inner transition elements

Representativeelements

Representative elements

Lanthanide series

Actinide series

Designing aPeriodic TableProcedure1. Collect pens and pencils

from everyone in yourclass.

2. Decide which properties ofthe pens and pencils youwill use to organize theminto a periodic table.Consider properties such ascolor, mass, or length.Then create your table.

Analysis1. Explain how your periodic

table is similar to the peri-odic table of the elements.

2. If your classmates broughtdifferent pens or pencils toclass tomorrow, howwould you organize themon your periodic table?

Figure 2 The periodic table isdivided into sections. Traditionally,the lanthanides and actinides areplaced below the table so that thetable will not be as wide. Theseelements have similar properties.

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436 CHAPTER 15 The Periodic Table

PERIODIC TABLE OF THE ELEMENTS

Hydrogen

1

H1.008

Element

Atomic number State ofmatter

Hydrogen

1

H1.008

Lithium

3

Li6.941

Sodium

11

Na22.990

Potassium

19

K39.098

Rubidium

37

Rb85.468

Cesium

55

Cs132.905

Francium

87

Fr(223)

Radium

88

Ra(226)

Actinium

89

Ac(227)

Rutherfordium

104

Rf(261)

Barium

56

Ba137.327

Lanthanum

57

La138.906

Hafnium

72

Hf178.49

Tantalum

73

Ta180.948

Dubnium

105

Db(262)

Seaborgium

106

Sg(266)

Hassium

108

Hs(277)

Meitnerium

109

Mt(268)

Bohrium

107

Bh(264)

Tungsten

74

W183.84

Rhenium

75

Re186.207

Osmium

76

Os190.23

Iridium

77

Ir192.217

Strontium

38

Sr87.62

Yttrium

39

Y88.906

Zirconium

40

Zr91.224

Niobium

41

Nb92.906

Molybdenum

42

Mo95.94

Calcium

20

Ca40.078

Scandium

21

Sc44.956

Titanium

22

Ti47.867

Vanadium

23

V50.942

Chromium

24

Cr51.996

Technetium

43

Tc(98)

Ruthenium

44

Ru101.07

Manganese

25

Mn54.938

Iron

26

Fe55.845

Cobalt

27

Co58.933

Rhodium

45

Rh102.906

Magnesium

12

Mg24.305

Beryllium

4

Be9.012

1

1 2

2

3

4

5

6

7

93 4 5 6 7

Gas

Liquid

Solid

Synthetic

8

The number in parentheses is the mass number of the longest-lived isotope for that element.

The first three symbols tell you the state of matter of the element at room temperature. The fourth symbol identifies elements that are not present in significant amounts on Earth. Useful amounts are made synthetically.

The arrow shows where these elements would fit into the periodic table. They are moved to the bottom of the table to save space.

Rows of elements are called periods. Atomic number increases across a period.

Columns of elements are called groups. Elements in the same group have similar chemical properties.

Cerium

58

Ce140.116

Thorium

9